Power semiconductor devices are semiconductor devices used as switches or rectifiers in power electronic circuits.
The realm of power devices is divided into two main categories: The two-terminal devices (diodes), whose state is completely dependent on the external power circuit they are connected to; and the three-terminal devices, whose state is not only dependent on their external power circuit, but also on the signal on their driving terminal (gate or base). Transistors and thyristors belong to that category.
A second classification is less obvious, but has a strong influence on device performance: Some devices are majority carrier devices such as Schottky diode and MOSFET, while the others are minority carrier devices such as Thyristor, bipolar transistor, and IGBT. The former use only one type of charge carriers, while the latter use both (i.e. electrons and holes). The majority carrier devices are faster, but the charge injection of minority carrier devices allows for better On-state performance.